This invention relates to a keypad layout with strokes assigned to keys in a novel and convenient manner for input of ideographic text such as Chinese and Japanese.
For many years developers of complete keyboards have struggled with the problem of input of Chinese and Japanese text, because these languages use a very large alphabet of characters, more than 13,000 characters, and it is a great problem attempting to devise a keyboard that permits entry of such a large variety of characters from a more limited number of keys.
Many proposals exist for using an intentionally standard QWERTY keyboard for entry of ideograph text (e.g. Chinese and Japanese). Such a keyboard has about 36 keys, plus some punctuation keys, and this is a manageable number of keys for two-handed operation and for convenience of size in a desktop system. Examples of such input systems can be found in U.S. Pat. No. 4,954,955 of Chiu and is in Chinese Patent No. CN1036548C. The former of these has a set of keys designated for entry of strokes and another set for entry of radicals (multi-stroke character sub-elements). It also assigns one frequently used character to each key which can be entered using a shift key. The proposed also divides the keyboard into a left-hand set of keys and a right-hand set of keys and enables stroke coding and component coding.
The increasing demand for smaller and smaller devices is driving keyboard design towards one-handed keypad data entry. A keypad typically has only 12 keys (but may have as many as 16 or 24 keys) and is typically used on telephones, mobile telephones and similar diveces where one hand of the user is engaged in holding the device (e.g. the telephone earpiece with mobile phone handset) and only one hand is free for data entry.
U.S. Pat. No. 5,952,942 which issued on Sep. 14, 1999 (assigned to the assignee of the present invention) proposes a method of Chinese text entry using a keypad and using the widely-established pinyin scheme of phonetic representation of Chinese text form a standard US-Style telephone keypad where each key has letters of the roman alphabet assigned to it. Software as is described in U.S. patent application Ser. No. 08/806,504 of Chen (assigned to the assignee of the present invention) operates to disambiguate the intended pinyin entry.
Although pinyin data entry is a useful solution, not all Chinese speakers are well versed in pinyin data entry. The more natural form of Chinese data entry is a stroke-based writing form, directly creating characters from strokes. The Chinese government has published a national standard of strokes and character components, which lists 560 standardized strokes and character components. In the standard, a character component comprises from 1 to 16 strokes.
Others have proposed schemes of character entry using a 9 or 10-key keypad which are based on entry of strokes and other character components.
As a first example, Chinese Patent No. CN1015214B assigns Chinese representations of numbers to keys, (xe2x88x92, =, xe2x89xa1, ) and uses the same keys for entry of strokes that have some similarity to the Chinese numerals. As an example, the character for xe2x80x9c1xe2x80x9d is a single horizontal stroke, so the key xe2x80x9c1xe2x80x9d is used for entry of single horizontal strokes, while the character for xe2x80x9c9xe2x80x9d () includes a right hook. It is a drawback of this scheme, however, that the Chinese characters for digits xe2x80x9c0xe2x80x9d to xe2x80x9c9xe2x80x9d do not encompass all the strokes required for a full range of character entry. It is a further drawback that a user may be confused over which key to press between two keys that use broadly similar strokes.
Another scheme is described in Chinese Patent Application No. 93102274, in which the phonetic association that a user perceives in a given digit is the association to be used in generating a character component. As an example, in Chinese, xe2x80x9c3xe2x80x9d is pronounced xe2x80x9csanxe2x80x9d and is commonly associated with xe2x80x9csan dian suixe2x80x9d which is the phonetic pronunciation for xe2x80x9cthree dotsxe2x80x9d so the scheme requires that key 3 is used for entry of a dot.
Problems with the above scheme lie in the constraint that they rely on the user""s own acquired associations that the user makes between digits and strokes.
A scheme that is not constrained by such previously learned associations is described in Chinese Patent Applications No. CN1142631A and CN1120695A, in which three categories of character components are mapped to keys on a keypad:xe2x80x94lines, corners and boxes. Whereas such a scheme is flexible, it does not have any inherent ergonomic efficiency, as there is no intuitive relationship between keys and character components. The user must learn these associations himself. Also, in decoding key entry, it is a drawback that the user must enter not just one to three initiated strokes, but also two or one of the last strokes of a character. This requirement causes the user to have to think ahead to the last stroke of a character to enable complete character entry. It is believed that this requirement is imposed for disambiguation because the selection of strokes and boxes inadequately spans the range of stroke components required for data entry and therefore inadvertently disambiguates strokes.
There is a need for an improved keypad for stroke-based ideographic text entry where each key has a clear and reasonably unambiguous stroke meaning, where the selection of strokes assigned to keys thoroughly spans the universe of possible strokes and where there is an intuitive association in the user""s mind between a key or its location and the stroke or component it represents.